In the HSS▸ timetables, it's shown as a 2330 start, so it's an evening service, running Mon-Fri, with different timings on Friday. Those differerent timings would show up on a Saturday morning in the local timetable.
Interestingly, they don't: they only appear on page 26 (the last of the 'Mondays to Fridays' entries), not on page 27 (the first of the 'Saturdays' entries).